• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.90-93
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• 2013

최근 IT Service 에는 SNS 즉, Social Network Service가 주를 이루고 있다. Facebook, Twitter 등 자신의 일상을 친구들과 공유하는 웹 기반 Service가 사람들에게 많이 이용되고 인기를 끌고 있다. SNS system이 일반화되어 가면서, 보다 전문적이고 국소적인 분야에 특성화되어 발전되어 나갈 것으로 보이며, 이러한 SNS 시스템을 최적화 하기 위해 SNS 프로토타입을 직접 개발해 볼 필요가 있다. 본 논문에서는 학교 캠퍼스 정도 규모의 서비스를 위한 웹 기반의 SNS들이 어떠한 구조로 이루어져 있으며, 어떠한 원리로 동작하는지 알아보고, Server, DataBase, PHP 를 이용하여 웹 기반 SNS 시스템을 직접 구현하고 시연해 봄으로써 SNS System에 대한 이해를 해보고, SNS system에 대한 향후 방향을 모색해 보도록 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.1096-1097
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• 2023

본 연구에서는 항만 교통 혼잡 문제를 해결하기 위해 최적화와 관련된 요소와 트럭 운전기사와 터미널 사이의 협상과 관련된 요소를 새로운 방식으로 고려한 중장기 및 실시간 스케줄링 모델을 제시한다. 중장기 스케줄링 모델은 몬테카를로 시뮬레이션, 실시간 스케줄링 모델은 알파고 제로의 원리와 베이즈 정리를 이용하여 구현했다. 실험 결과 제시된 알파고 제로를 이용한 실시간 스케줄링 시스템이 화물차 평균 지연시간을 30분에서 4분으로 대폭 줄여 지연 시간을 최소화하는 것을 입증했다. 실험 관련 코드는 다음 주소에서 확인할 수 있다 : https://github.com/yulleta/Application_of_AlphaGo-Zero_to_port_arrival_scheduling

• The Journal of Korean Association of Computer Education
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• v.16 no.5
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• pp.9-16
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• 2013

Computational thinking is an ability to resolve problems that may be applied to the various real world problems and is regarded as the core of computer science. Computational thinking may be improved through experiences of analyzing problems and of selecting, applying, and modeling strategies appropriate for problem-solving. In order to enhance computational thinking of learners, it is important to provide experiences of solving various problems. This study designed puzzle based learning in order to educate learners principles of problem solving, let them have experiences of interest and insight, and provide them with problem solving experiences. The puzzle questions used for learning were classified into six types - constraints, optimization, probability, statistics, pattern recognition, and strategies. These questions were applied to Informatics gifted elementary students and, after their education, their computational thinking and problem solving inventory significantly improved.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.5
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• pp.99-105
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• 2014

A reference spur suppressed PLL with two-symmetrical loops without changing the bandwidth which is optimized to suppress phase noise and reduce locking time has been designed. The principle of suppressing a reference signal spur is to stabilize the input voltage of voltage controlled oscillator (VCO). The proposed PLL consists of a phase-frequency detector(PFD) which has two outputs, two charge pumps(CP), two loop filters(LF), a divider and a VCO which has two inputs. Simulation results with $0.18{\mu}m$ CMOS process show that the reference spur is approximately suppressed to 1/2 of the reference spur in a conventional PLL. Even though there is a 5% process variation in the magnitude of R and C, the simulation result shows that the reference spur is still suppressed to 1/2 of the reference spur in a conventional PLL. The power consumption is 6.3mW at the power supply of 1.8V.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.11
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• pp.787-797
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• 2015

In this paper, a cochlea-inspired artificial filter bank(CAFB) was developed in order to efficiently acquire dynamic response of structure, and it was also evaluated via dynamic response experiments. To sort out signals containing significant modal information from all the dynamic responses of structure, it was made to adopt a band-pass filter optimizing algorithm(BOA) and a peak-picking algorithm (PPA). Optimally designed on the basis of El-centro and Kobe earthquake signals, it was then embedded into the wireless multi-measurement system(WiMMS). In order to evaluate the performance of the developed CAFB, a vibration test was conducted using the El-centro and Kobe earthquake signals, and structural responses of a two-span bridge were obtained and analyzed simultaneously by both a wired measurement system and a CAFB-based WiMMS. The test results showed that the compressed dynamic responses acquired by the CAFB-based WiMMS matched with those of the wired system, and they included significant modal information of the two-span bridge. Therefore this study showed that the developed CAFB could be used as a new, economic, and efficient measurement device for wireless sensor networks(WSNs) based real time structural health monitoring because it could reconstruct the whole dynamic response using the compressed dynamic response with significant modal information.

• Journal of Digital Convergence
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• v.19 no.6
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• pp.293-297
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• 2021

This paper applies the natural history contents of the Science Museum and combines the Gestalt theory to develop the butterfly arrangement structure of the butterfly sample box and the butterfly sample information necessary for the sample box as AR (Augmented Reality). Existing analog sample information is expressed as digital information by combining place, butterfly information, and graph to maximize the effect of digital diorama exhibition. Digital natural history information is increased or decreased, and an environment optimized for real samples and suitability is constructed, and natural history contents are arranged in the principles of collectiveness, closure, simplicity, and continuity using the Gestalt visual perception principle to increase attention and increase the attention of butterfly collection information. Was applied as an application plan of AR.

• Journal of the Korean Institute of Gas
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• v.26 no.2
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• pp.9-13
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• 2022

Electric wheelchairs, the output from the motor is mainly applied to a speed reducer using a power transmission device such as a belt or a chain. However, although a speed reducer using a belt or chain is a simple device, it occupies a lot of space and has a space limitation, so it is not suitable for an electric wheelchair driving part. However, since the speed reducer of the planetary gear type is decelerated on the same axis, the volume can be reduced, so the space constraint is less than that of the belt or chain type reducer. Therefore, in this study, a driving part that can obtain great propulsion with a speed reducer using a planetary gear type was developed through a study on the driving part of a wheelchair that can be switched between manual and electric. Accordingly, the tooth shape of the planetary gear applied to the reducer was designed using the Kisssoft program. In addition, the drive part was designed to be applicable to the existing wheelchair wheels, and the mechanism was optimized for the manual/electric switching principle and operation principle of the drive part. Based on the research contents, the final design and manufacture of the wheelchair reducer drive unit in the form of a planetary gear having one sun gear, two planetary gears and one ring gear was carried out.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.3
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• pp.200-209
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• 2013

In this paper, the types of B-dot controller and the review results of B-dot controller stability are summarized. Also, it is confirmed that B-dot controller is very useful and essential tool when a dawn-dusk low earth orbit(LEO) large satellite has especially to capture the Sun for a required power supply in a reliable way after anomaly and that its algorithm is very simple for on-board implementation. New physical interpretation of B-dot controller is presented as a result of extensive theoretical investigation introducing the concept of transient control torque and steady state control torque. Also, the failure effect analysis results of magnetic torquers as well as a simulation verification are included. And the design recommendation for optimal design is provided to cope with the failure of magnetic torquer. Nonlinear simulation results are included to justify its capability as well as its performance for an application to a dawn-dusk LEO large satellite.

• Journal of Korea Water Resources Association
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• v.46 no.6
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• pp.597-611
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• 2013

This paper presents the methodology for construction of time-area curve via the width function and thereby rational estimation of time of concentration and storage coefficient of Clark model within the framework of method of moments. To this end time-area curve is built by rescaling the grid-based width function under the assumption of pure translation and then the analytical expressions for two parameters of Clark model are proposed in terms of method of moments. The methodology in this study based on the analytical expressions mentioned before is compared with both (1) the traditional optimization method of Clark model provided by HEC-1 in which the symmetric time-area curve is used and the difference between observed and simulated hydrographs is minimized (2) and the same optimization method but replacing time-area curve with rescaled width function in respect of peak discharge and time to peak of simulated direct runoff hydrographs and their efficiency coefficient relative to the observed ones. The following points are worth of emphasizing: (1) The optimization method by HEC-1 with rescaled width function among others results in the parameters well reflecting the observed runoff hydrograph with respect to peak discharge coordinates and coefficient of efficiency; (2) For the better application of Clark model it is recommended to use the time-area curve capable of accounting for irregular drainage structure of a river basin such as rescaled width function instead of symmetric time-area curve by HEC-1; (3) Moment-based methodology with rescaled width function developed in this study also gives rise to satisfactory simulation results in terms of peak discharge coordinates and coefficient of efficiency. Especially the mean velocities estimated from this method, characterizing the translation effect of time-area curve, are well consistent with the field surveying results for the points of interest in this study; (4) It is confirmed that the moment-based methodology could be an effective tool for quantitative assessment of translation and storage effects of natural river basin; (5) The runoff hydrographs simulated by the moment-based methodology tend to be more right skewed relative to the observed ones and have lower peaks. It is inferred that this is due to consideration of only one mean velocity in the parameter estimation. Further research is required to combine the hydrodynamic heterogeneity between hillslope and channel network into the construction of time-area curve.

• Korean Journal of Cognitive Science
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• v.12 no.1_2
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• pp.77-89
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• 2001

Applying perceptual hierarchy of facial feature points, a neural network model for recognizing facial expressions was designed. Input data were convolution values of 150 facial expression pictures by Gabor-filters of 5 different sizes and 8 different orientations for each of 39 mesh points defined by MPEG-4 SNHC (Synthetic/Natural Hybrid Coding). A set of multiple regression analyses was performed with the rating value of the affective states for each facial expression and the Gabor-filtered values of 39 feature points. The results show that the pleasure-displeasure dimension of affective states is mainly related to the feature points around the mouth and the eyebrows, while a arousal-sleep dimension is closely related to the feature points around eyes. For the filter sizes. the affective states were found to be mostly related to the low spatial frequency. and for the filter orientations. the oblique orientations. An optimized neural network model was designed on the basis of these results by reducing original 1560(39x5x8) input elements to 400(25x2x8) The optimized model could predict human affective rating values. up to the correlation value of 0.886 for the pleasure-displeasure, and 0.631 for the arousal-sleep. Mapping the results of the optimized model to the six basic emotional categories (happy, sad, fear, angry, surprised, disgusted) fit 74% of human responses. Results of this study imply that, using human principles of recognizing facial expressions, a system for recognizing facial expressions can be optimized even with a a relatively little amount of information.